Vinylpyridine-mercaptan adducts



Patented Aug. 19, 1952 UNITED STATES PATENT oFF'i-CEVINYLPYRIDINE-MERCAPTAN ADDUCTS William Howells Vinton, Wilmington,Del., as-

signor to E. I. duPont de Nemours & Company, Wilmington, Del., acorporation of Delaware No Drawing. Application August 4,1945,

' Serial No. 609,029

in R is a monovalent hydrocarbon radical, is

reacted with a C-vinyl heterocyclic amine in which the amine group ispart of the heterocyclic ring and the vinyl group is attached to nuclearcarbon, and the resulting reaction product which is a C-substitutedheterocyclic amine having, attached to nuclear carbon, a'group of theformula RSCH2CH2, wherein R is as above, and havingthe amino group aspart of the heterocyclic ring is isolated.

Under-the usual conditions of this reaction approximately equimolarquantities of the mercaptan and the C-vinyl .heterocyclic amine arebrought together in intimate contact at room temperature either in thepresence or absence of ultraviolet light and thereaction is continueduntil a substantial proportion of the mercaptan has reacted with thevinyl compound. Thiscan be readily determined by titrating an aliquotportion of vthe reaction mixture with iodine according to the standardanalytical procedure for thiol determination. After the completion ofthe reaction the product; is then isolated and purified by vacuumdistillation or crystallization. The reaction is-generally exothermicand can be controlled by externalcooling or by addinsany or both of thereactants to the reaction mixture at such a rate that excessivetemperatures are not developed. Frequently it is desirable to have avinyl polymerization inhibitor present in the reaction mixture toprevent excessive polymer formation in the C-vinyl heterocyclic amine.

The invention is illustrated by the following examples in which partsare by weight.-

In a transparent Vycor glass reaction vessel chilled in Dry Ice-acetonemixture were placed 48.0 parts (1.00 mole) of purified methyl mer-.

captan and 95 parts (0.90 mole) of freshly distilled 2-vinylpyridinestabilized with a trace of l'iydroquinone.v Catalytic amounts (0.1 part)of A'still further object is the preparation :6 :Claims. ('Cl. 260-290)benzoyl peroxide and diphenyl disulfide were added to the reactionmixture which was then permitted to warm up to room temperature and toreflux gently while being irradiated with an H-4 ultra-violet lamp.Irradiation was continued at room temperature for 1a hours, after whichtime an aliquot portion was removed and.

titrated with iodine. The titration indicated that 87.6% of the methylmercaptan had reacted. The mixture was then distilled under nitrogen ina distilling apparatus. After removal of unreacted methyl mercaptan, thebulk of the material distilled uniformly at 85.5 C. at 1.5 mm. 'The product, 2- [beta-methylthioethyl] pyridine, was

a water-white liquid of characteristic odor and amounted to 96.6 partsor of theory;

Analysis: Calculated for CsHnNS: C, 62.8%; H, 7.19%.

Found: C, 63.15%, 63.06%; H, 7.76%, 7.66%. The following values werealso determined for this product: specific gravity Example 2 refractiveindex at In a transparent Vycorf glass reaction vessel fitted with areflux condenser and a stirrer were placed 45.0 parts 0.50 mole) ofredistilled tertiary butyl mercaptan and 52.5 parts (0.50 mole) offreshly distilled 2-vinylpyridine stabilized with a trace ofhydroquinone. The reaction mixture was then irradiated for 10 hours atroom temperature with ultra-violet light generated byan I-I-4Jlamp. Atthe end of this time, a portion of the tertiary butyl mercaptan appearedto have reacted as determined by iodine titration of an aliquot portion.The reaction mixture was then transferred to a distillationapparatusj'and'distilled under nitrogen. Unreacted tertiary butylmercaptan and unreacted 2-vinylpyridine were removed as the firstfractions, and the residual liquid, boiling from 108 to 122 C. at 3 mm.pressure, amounted to '11 parts (11.3% of theory) of 2-[beta-(butylthio)ethyllp'yridine; The product" was a pale yellow-brown liquid ofcharac-'" teristic unpleasant odor having the determined specificgravity V 2 o 0. of 0.9970

and refractive index at 25 our 1.5268.

:Found: N -(Dumas), 7.51%, 7,23 3;.

Example 3 In a reaction vessel fitted with a stirring apparatus,thermometer and addition means was placed 124,0 parts (1.00 mole) ofbenzyl mercaptan. One hundred five parts (1.00 mole) of2-vinylpyridine.stabilized with a. trace. oflhydroquinone was addedrapidly to the stirred reaction:

mixture, and the exothermic reaction which occurred was checked at 105C. by cooling external.

ly until further exothermic changes were no longer evident. The crudereactionproduct was :dis&

tilled under nitrogen in a distillation apparatus.

and after removal of unreactedi2vinylpyridihe the main portion of theproduct. distilled at.

146 C. at 1 mm. pressure. There was obtained 154.6 parts (67.5% oftheory) ofQ-[beta-(benzyl-a thio)ethyl]pyridine having a faintyellowcolor and a characteristic unpleasant odor. The prod uct has aspecific gravity 7 Qaof. were;

and a'refractiveindexat'25""Ci of 1150201- Analysis: CalculatedforflCitHi'sNsz 6.12%.

Found. 'N""(Dumas') .6565 6544 Example 4.

Ina-reaction vessel fittedwithastirring appae ratus: .a thermometer-aridan addition 'meanswa-s' placed"62'.0 parts" (0l50tmole')Ofrp=thiocresol1 (pftolyl mercaptan). Withrrapid 'stirring there-was'added" slowly 5225 parts" (0'150111016). of iresh'ly di'stilled"2vinylpyridinastabilizedwitlr a t'ra'ceof' hydroquinone: After about /3'of the' vinyl pyridine hadb'eenadded; a' rapidexothermic'ireaction beganand the temperature was allowed to rise-to 65 "C. and held'at thattemperature byexterna'l cooling until theexothermic" reaction ceased.The titration of an" aliquot portion showed that the reaction was 991%complete. The product was then distilled in a .vacuum distillationapparatus and 109 parts or 95.5%. oftheory of 2- [beta- (p-tolylthio)ethyllpyridine b'oiling at l52-l53 C. at 0.7 mnnwaszobtained. Theproduct was apale yellowliquid possessing a. faintly unpleasant" odor?It had a specific gravity- 4 The product is a light yellow liquid whichhas a specific gravity 0 C. of 0.9634

and a refractive index at 25 C. of 1.5038. 1.5038;

Analysis::"Calcu1ated for C'i9H33NS: N: 4.56% Found: N (Dumas), 5.10%.

Example 6 Irrareaction-vessel fitted with a stirring mechanism,-..an.additionalmeans, and a thermometer were placedA0.0-=:parts (0.25 mole)of 2-naphthyl mercaptamandr about parts of dry chlorobenzene. To the.rapidly-stirred solution Was adddislowly 2625' parts (0.25 mole) of2-vinylpyridine stabilized with a trace of hydroquinone. An: exothermicreaction occurred in which the maximum temperature reached was 70 C.After cooling: tot-room temperature the. titration rofian aliquotportion with::iodine solution' showedsthat thezreactiorr was 94%?complete; The: chlorob'enzene waswremovedia'tz75 Cs under:v Water pump.

vacuum; The remaining productawas distilled;

ativa-cuum; distillation: apparatus under-"nitrogen.

and'i26z8spjartsa- (40.5 of itheory) of: 2--[beta-.-(2L-. naphthylthio)ethyllpyridine boiling; at: 168-r-170? C. art-0105 imm.iwasr.obtained'.Thewproduct was .a; viscousryellowaliquidshaving;arspecitfic-igravity;

templatedtthatitherreactiom describediisaoperativei with other C-vinylheterocyclic aminesiiniwhichi thesa'minocgroun ispart:ofitheiheterocyclic ring and thewinyl' group is a'ttaeliedunclean-carbon thereof; for: examples: SQVinylpyridin ee.4vinyl#pyridine; 2'.vinylquinoline;: ZEVinyIpiperidine; vinylpyrrolid-ine,= 5ie'tliyl 2 e vinyl-pyridin etc: Heterocyclicamines havingzthe aminonitrogen' asnthe only heteroatom are preferredi As aillustrated bytheiexamples both aliphatic andfaromaticz mercaptans are operable =fdrform= ing the products =o'f-"thia inventions: Other-= men-- captansaliphatic aromatic;and'alieyclic, maybe used 5 including ethylmercaptann propyl -mer captanaisopropyl merca-ptan; -n'-b'utyl -mercaptan; octylmercaptan;cycldhexyl mercaptan; l -phefnyl ethyl mercaptan, tHiOphllOhand'-1=xylyl merc'ap tan; Mreaptans fi-ee ffom eth ylnic-and acetyl enicunsaturatidn-s i. e free--ffo-zn non=arornatic unsaturationyarepreferredc Thereactiom oftheC vinylheterocyclic-.amine with 'the-mereaptancarr generally -be carrid out between: room '-temperaturei(20G2) and 200--'*C although temperaturem of--' '1'00" G? are generallysuffi'cient-s The 'reactiorris*carriedoutiusually atatmospher-iopressure although superatmosplieric' pressure may be usedifdesired. The reaction is ordinarily allowed to proceed until asubstantial proportiom: of thee: mercapta-mhas; reacted and thisrcan:beadetermi-ned:bmtitratiorrof an? aliquotportion'wofi;thes-rea-ctionz=mixture with iodine ace g, o'rth'e: commonianalytical .proceduresfon determininggthiolsaIii-marrying;outithereactiom dine boilingat;=l82?"C:;at10.l3:mm;.was;.obtained.to;formntliezproduutscofethisainventioniit isrfreei quently desirable tomake use of ultraviolet light either with or without photocatalysts, forexample, benzoyl peroxide and diphenyl disulfide, which are sometimesadded to assist the reaction.

The reaction may be carried out without added solvent or in the presenceof solvents which are inert to the reactants. Solvents which can be usedinclude chlorobenzene as illustrated by EX- ample 6. Other solventsinclude toluene, ethanol, butanol, benzene and the like.

It is frequently desirable to include in the re-' action mixture a smallamount of a polymerization inhibitor, for example, hydroquinone, toprevent excessive polymerization of the C-vinyl heterocyclic amines.

The compounds of this invention are useful as dyestuff intermediates,pesticides, and for pharmaceutical purposes.

The above description and examples are intended to be illustrative only.Any modification thereof or variation therefrom which conforms to thespirit of the invention is intended to be included within the scope ofthe claims.

What is claimed is:

1. 2-Benzy1thioethylpyridine -cmcmscmoim 2. A pyridine having on nuclearcarbon at position 2 a substituent of the formula RSCHzCHzwherein R is amonovalent saturated hydrocarbon radical.

3. A pyridine having on nuclear carbon a substituent of the formulaRSCH2CH2- wherein R is a monovalent saturated hydrocarbon radical.

4. A pyridine having on nuclear carbon a sub- REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,367,898 Strauss Jan. 10, 19201,672,253 Giles June 5, 1928 1,825,662 Hale Oct. 6, 1931 2,352,435Hoeffelman June 27, 1944 2,398,479 Vaughan Apr. 16, 1946 2,409,806 ShiveOct. 22, 1946 OTHER REFERENCES Benchte,vo1. 20 (1887), page 1643.

Maier: Das Pyridine and seine Derivatives (1934),: 168.

Mayo Chem. Reviews, vol. 27, 1940, pp. 387-394.

Sidgwick: Organic Chemistry of Nitrogen (1942) DD. 522, 523 and 528.

J. Am. Chem. Soc. (1941) Dec. 8, 1941, vol. 63,

Sidgwick: Organic Chemistry of Nitrogen (1937) pp. 516 and 517.

1. 2-BENZYLTHIOETHYLPYRIDINE